The goal of this project is to evaluate physical properties (size, degree of crystallinity and hygroscopicity) and feasibility of inhalation exposure of four different cellulose nanomaterials, which appear to be bio-persistent in the lung. These studies include determination of Over 11,000 synthetic turf fields exist in the U.S., with approximately 1,200 being added annually. The component of turf that is of most concern is crumb rubber infill, made from recycled automotive tires. Crumb rubber contains numerous potential carcinogenic and toxic substances, yet the exposure of people playing on installed fields to these hazardous components is not well understood. Information gained from NTP toxicology studies will provide public health agencies with information to inform exposure and health assessments. There are significant challenges to the conduct of toxicology studies due to the physical nature of the crumb rubber material. In addition to informing feasibility of conduct of future NTP toxicity studies and provide information on systemic exposure by various routes, these data will aid other researchers design toxicity studies and interpret the resulting data. Keywords: toxicity, nanocrystalline cellulose, nanomaterials, inhalation, lung